1. Field of the Invention
The present invention relates generally to a plasma ignition system, and more particularly to a configuration of the plasma ignition system in which the single condenser storing the high ignition energy for each cylinder is connected to the output terminal of a DC--DC converter in order to perform plasma ignition by applying the current discharged from the condenser to the space between the electrodes of the respective spark plugs through respective boosting transformers when the respective switching units are turned on at the predetermined ignition times.
2. Description of the Prior Art
The plasma ignition system has been developed as a means of obtaining reliable ignition and for improving the reliability of fuel combustion even under engine operating conditions such that combustion is liable to be unstable when the engine is operated within a light-load region or when the mixture of air and fuel is weak.
In prior-art plasma ignition systems, a current flowing from a battery to the primary winding of an ignition coil is turned on or off by a contact point actuated according to the crankshaft revolution in order to generate high tension pulse signals in the secondary winding of the coil. These high voltage pulses are sent to the distributor through a diode and are next applied, in order, to the respective spark plugs through the respective high-tension cables. Accordingly, a spark is generated between the electrodes of the spark plug, and subsequently a high-energy electric charge of a relatively low voltage is passed from a plasma ignition power supply unit between the electrodes for a short period of time to generate a plasma.
In the prior-art plasma ignition system, however, since the output voltage from the plasma ignition power supply unit is simultaneously applied to all the spark plugs, an unwanted discharge can be generated between the electrodes at times other than the desired ignition times, thus resulting in the problem of irregular discharge.
Further, a large amount of power is consumed within the diode.
Furthermore, in the prior-art plasma ignition system, since the high tension cables are connected between the spark plug and the power supply unit, an impulsive current flows through the cables, thus resulting in another problem such that strong wide-band electrical noise is generated from the high tension cables.
A more detailed description of the prior-art plasma ignition system will be made under DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT with reference to the attached drawings.